Galactic center star S2: the top panel shows the observed squared visibilities and closure phases. The baseline coverage is shown in the small inset. The bottom panel displays the 3σ detection limit for companions of S2 as function of separation applying two different methods (Absil et al. 2011; Gallenne et al. 2015). Companions brighter than Δm_K = 3 mag, corresponding to a limiting magnitude of m_K = 17.1 mag, are ruled out.